A cellular communication using a cell formed by a base station is used as one of wireless communication methods. Moreover, an ad hoc network is sometimes formed with an ad hoc communication made by a plurality of communication apparatuses not via a base station. However, since a cellular communication and an ad hoc communication use different protocols, user data (U-plane information) transmitted/received by a cellular network cannot be directly transmitted to an ad hoc network. Accordingly, as illustrated in FIG. 1, a relay apparatus 2 for including user data within a packet transmitted/received in a cellular communication in a frame that can be transmitted/received in an ad hoc communication and for relaying the frame to an ad hoc network is used.
FIG. 2 illustrates an example of a protocol used when user data is relayed from a system using a cellular communication to an ad hoc network. A central apparatus 1 transmits the user data to a base station 5 that forms a communication area of a communication apparatus that is an end user. A wired communication using a protocol such as Ether PHY (Ethernet Physical layer), Ether MAC (Ether Media Access Control), IP (Internet Protocol) or the like is made between the central apparatus 1 and the base station 5. The base station 5 generates a packet including the user data received from the central apparatus 1, and transmits the packet to a communication apparatus and a relay apparatus within a cell by using 3G (3rd Generation) PHY and 3G MAC. Here, the base station 5 generates 3G MAC information by using IP information received from the central apparatus 1. The relay apparatus 2 generates an ad hoc frame including the data of the packet received from the base station 5, and transmits the frame to a communication apparatus within the ad hoc network by using LAN PHY (Local Area Network PHY) and LAN MAC. In this way, user data transmitted/received by a system that makes a cellular communication can be received or transmitted by a communication apparatus within an ad hoc network.
For a transmission of user data, a method for distributing contents received via a broadcast wave with a wireless LAN communication is proposed. Also a system for receiving information of government authorities and for transmitting data on the received information to communication apparatuses that join a system is proposed as a broadcast system used at the time of a disaster or the like. Additionally, a method for mapping a different partition included in broadcast system information onto a shared transport channel or a broadcast transport channel is known. Furthermore, a method for shortening a delay caused when a wireless bearer is established by notifying a mobile terminal of settings of an available wireless bearer is proposed for a wireless communication.